Diaphragm for sound-reproducing apparatus



J. A. STEURER DIAPHRAGM FOR SOUND REPRODUCING APPARATUS June 26, 1923.

Filed May 29, 1922 avwemtoz \Hifllk 3 0 a k z m M Z r 6 3 M PatentedJune 26, 1923.

UNITED STATES PATENT OFFICE.

JOHN A. STEURER, OF NEW YORK, N. Y.

Application filed. May 29,

To all whom it may concern:

Be it known that I, JOHN A. STE RER, a citizen of the United States,residing at New York, in the county of New York and State of New York,have invented certain new and useful Im rovements in Diaphragms forSoundeproducing Apparatus; and I do hereby declare the following to be afull, clear, and exact description of the invention, such as will enableothers skilled in the art to which it appertains to make and use thesame.

My invention consists in the novel features hereinafter described,reference being had to the accompanying drawing which illustratesseveral embodiments of the invention selected by me' for purposes ofillustration' and the said invention'is fully disclosed in the followingdescription and claims.

The object of my invention is to provide a diaphragm suitable for use inall forms of sound reproducing apparatus, such as phonographs or talkingmachines, telephones, amplifying devices for loud speakers, for use withwireless or other telephonic apparatus, or for any other purposes forthe reproduction of sound, which shall be practically free from metallicresonance, and so-called blasts. and other objectionable noises, so thatit will transmit articulate speech, music, and other sounds clearly andaccuratel and render a true and sub-- stantially per ect reproduction ofthe sounds transmitted to it.

My improved diaphragm comprises a disc of non-absorbent sheet material,'such as metal, mica glass and the like,- provided on one or both faceswith a dried coating-of adhesive material having combined therewith, anddistributed substantially uniformly throughout, finely divided dampingmaterial, preferably in pulverulent form, which will clarify the soundintended to be transmitted by the diaphragm and eliminate the inherentand unintended metallic resonance, blasts and rattles, etc., produced inand by the material of the diaphragm body itself in so doing, saidcoating being disposed concentrically with the center of the diaphragmand extending to a greater or less extent toward the periphery, and be-1922. Serial No. 564,352.

ing preferably of circular form.. When the diaphragm is intended to besubjected to the direct action of magnets in sound reproducing oramplifying apparatus,the disc or body of the diaphragm will necessarilybe formed of a magnetic metal, such as soft iron or steel, although forother purposes, non-magnetic metals and other non-absorbent materialsmay be employed. The preferred adhesive substance which is employed is asolution of phenolic condensa-' tion product (such asbakelite, redmonolor 'condensite) in a suitable vehicle, through which is distributed andmixed finely powdered particlesof wood, cork, flock, vegetable ivory,carbon (charcoal, lamp black or gasblack), or any other suitable finelydivided material, which will produce the said clarifying effect.

In the accompanying drawings,

Fig. 1 represents a plan View of one form of diaphragm embodying myinvention.

Fig. 2 represents a sectional view of the same somewhat exaggerated inthickness in order to facilitate the graphic illustration of theinvention.

Fig. 3 is a plan view of another form of diaphragm embodying theinvention.

Fig. 4 is a sectional view of the same, similar to Fig. 2.

. Fig. 5 is 'a plan view of another form of diaphragm embodying myinvention.

.Fig. 6 represents a sectional view of the J same prepared in the samemanner as Figs.

2 and 4, for purposes of illustration.

In the form of my inventionillustrated in Figs. 1 and 2, 1 represents adisc or body of non-absorbent material, such as metal (iron, steel,aluminum, brass or other metal), glass, mica, celluloid or othersuitable non-metalli'c substance, of the desired size to fit theinstrument with which it is to be used. A suitable adhesive material,preferably a solution of phenolic condensation product, such asb-akelite, redmonol, or condensite, or the like, dissolved or dispersedin a suitable vehicle, is prepared and is combined with a finely divideddamping material, which may be powdered cork, powdered wood, powderedflock, vegetable lvory or carbon (charcoal, lamp black or gas black forexample) or with a combination of two or more of these substances. Thisadhesive material in liquid form combined with the finely divideddamping material, is applied as a coating, indicated at 2, to thenon-absorbent body, 1, of the diaphragm, so as to form an areaconcentric with the centre of the body, 1, and of any desired diameter.The adhesive material combined with the finely divided damping materialis permitted to dry upon the body, 1, of the diaphragm so as to form ahard, tough adhesive coating when dry, in which the finely dividedmaterial is distributed with the greatest possible uniformity. Thisadhesive coating may be applied to one or both faces of the body of thediaphragm, according to the particular use to which the diaphragm is tobe put. It will be under stood that the finely divided damping materialis not only uniformly distributed throughout the coating, but issubmerged in the coating so as to modify throughout the extent of thecoating the action, which is also a damping action, of the phenoliccondensation product, so that as each portion of the diaphragm vibrates,its tone producing qualities will be modified both by the phenoliccondensation product and the submerged finely divided particles of damping material, with the result that the tone is clarified and allmetallic resonance and blasts are eliminated.

In Figs. 3 and 4:, for example, I have lustrated a diaphragm or mainbody, indicated at i provided with the concentric damping coating,indicated at 2}, of considerably larger size than the coating 2 shown inFigs. 1 and 2, and applied in this instance to both faces of thediaphragm.

In some instances the diaphragm body may be provided with one one ormore con centric flutes or ribs formed by pressing the material out ofthe plane of the other portions of the body so as to form a groove onone face and rib or projection on the other face, circular in form andconcentric with the center of the diaphragm. Such a dia phragm body isillustrated in Figs. 5 and 6 at 1*, the concentric. ribs or flutes beingindicated at 3, and the body 1 is provided in this instance on bothfaces with the dried adhesive coating containing finely divided dampingmaterial, as above described, the coatings being indicated at 2"2, inFigs. 5 and 6.

Obviously where my improved diaphragm is to be subjected directly to theaction of magnets, as in certin forms of magneto electric soundreproducing or amplifying apparatus, the body, 1, is formed of a metalreadily attracted by such magnets, such as, for example, soft iron orsteel. diaphragms are employed with apparatus in which it is notsubjected directly to the ac.- tion of magnets, the main body may be ofWhere the" iron or steel, or it may be of other metals not affected bymagnets, or it may be formed of mica, glass, celluloid or othernon-metallic material.

The dried adhesive coating containing the damping material in powdered.form has the efl'ect of eliminating the metallic resonance of thediaphragm and the rattle, blast or other extraneous noises which are sofrequently produced by the vibration of diaphragms used for soundreproduction, so that the transmitted sounds intended to be reproducedby the diaphragm are actually reproduced clearly, distinctly and freefrom extraneous noises, distortions and objectionable metallic resonanceand blast. The use of my improved diaphra m facilitate the reproductionof the transmitted sounds with the greatest accuracy, clearness andmellowness and eliminates harsh over tones and other extraneous noises.

While I prefer to employ a solution of phenolic condensation product(preferably redmonol dissolved in a suitable vehicle) as the adhesivematerial, I do not wish to be limited to this particular material, asother adhesive substances may be employed with beneficial results, forexample, I may employ a solution of a natural resinous gum, such as sparvarnish or other varnish, or other similar adhesive material in which iscombined the finely divided damping material.

In carrying out my invention in its prefferred form, I prefer to useeither powdered cork or lamp black, or a combination of powdered corkand lamp black in combination with the solution of redmonol or othersuitable adhesive material. I prefer to employ as the adhesive materiala solution of phenolic condensation product and particularly redmonolfor the reason that it dries hard, and to all intents and purposesbecomes an integral part of the diaphragm so that it cannot be removedtherefrom, except by actually cutting it away. At the same time it isextremely tough so that it does not break, crack or splinter, and itreadily responds to the movements of the diaphragm body without thepossibility of becoming injured or separated from the body of thediaphragm under any conditions of use.

As before stated, the dried adhesive coating containing the finelydivided damping material is applied concentrically with the center ofthe diaphragm and may extend from the center toward the periphery to anydesiredextent. The greater the diameter of the dried adhesive dampingcoating, the

greater will be the damping effect upon the diaphragm, and by varyingthe diameter of the dried adhesive damping coating the diaphragm may beadjusted with respect to the particular instrument or sound reproducinging the vibrations of the non-absorbent body of the diaphragm, producingan entirely different effect from that which would be produced by anuninterrupted coating of the adhesive 'material alone. 7

Obviously the use of a metal body for a diaphragm is highly desirable onaccount of its strength and uniformity, but also obviously metaldiaphragms have heretofore been most subject to objectionable metallicresonance, rattle, blasts and so forth, before referred to. For thisreason other substances than metal have been resorted to in constructmgdlaphragms where this was poss ble, as 1n talking machines and othersound reproducing apparatus, in which the action of magnetism plays nonecessary part. A diaphragm constructed in accordance with my inventionwith a metal disc or body provided with the described concentriccoating, completely eliminates the objectionable features of metallicresonance, rattles, blasts, etc., heretofore experienced with metallicdiaphragms, while presenting the characteristics of uniformity anddurability due to the metallic body, and further by employing a metalaffected by magnetic action, the beneficial results of my improveddiaphragm can be extended to all forms of. electromagnetic soundreproducing apparatus such as the ordinary telephone, the wirelesstelephone, electric amplifiers: for telephonic receivers, and otherforms of electromagnetic sound amplifiers including those in which it isnecessary to use a diaphragm which will be directly affected by magneticattraction.

The described adhesive coating may also be of any desired thicknessdepending upon the damping efi'ect desired, and it may be tric coatingcomposed of dried liquid ad-. hesive material, combined with finelydivided damping material, distributed substantially uniformlytherethrough, and submerged therein.

2. As a new article of manufacture, a diaphragm for sound reproducingapparatus comprising a disc of non-absorbent material, provided on atleast one face with a concentric coating, composed of dried liquidresinous adhesive material, combined with finely divided dampingmaterial, distributed substantially uniformly therethrough, andsubmerged therein.

3. As a new article of manufacture, a diaphragm for sound reproducingapparatus, comprising a disc of non-absorbent material provided on atleast one face with a concentric coating of dried liquid adhesiveconsisting of a phenolic condensation product dissolved in a suitablevolatile vehicle and having combined therewith finely divided particlesof damping material distributed substantially uniformly throughout saidcoating, and submerged therein.

4:. As a new article of manufacture a diaphragm for sound reproducingapparatus, comprisinga disc of non-absorbent material provided on atleast one face with a concentric coating of dried liquid adhesivematerial consisting of a phenolic condensation product dissolved in avolatile vehicle, and combined with finely divided cork, distributedsubstantially uniformly throughout the coating, and submerged therein.

5. As a new article of manufacture a diaphragm for sound reproducingapparatus, comprising a disc of non-absorbent material provided on at,least one face with a concentric coating of dried liquid adhesivematerial consisting of a phenolic condensation product dissolved in avolatile vehicle, and combined with finely divided cork, and lamp black,distributed substantially uniformly throughout the coating, andsubmerged therein.

6. As a new article of manufacture 2. diaphragm for sound reproducingapparatus, comprising a disc of non-absorbent material provided on atleast one face with a concentric coating of dried liquid adhesivematerial comprising a phenolic condensation product dissolved in avolatile vehicle.

7 As a new article of manufacture. a diaphragm comprising a disc ofmagnetic metal provided on. at least one face with a concern triccoating of dried liquid adhesive material, consisting of a phenoliccondensation product dissolved in a volatile vehicle.

- 8. As a new article of manufacture, a diaphragm comprising a disc ofmagnetic metal provided on at least one face with a concentric coatingcomposed of dried liquid adhesive material, combined with finely divideddamping material, distributed substantially uniformly throughout thecoating,

and submerged therein.

9. As a new article of manufacture, a diaphragm comprising a disc ofmagnetic metal .3 provided on at least one face With a concentriccoating composed of dried liquid adhesive material, consisting of aphenolic condensation product dissolved in a volatile vehicle, combinedwith finely divided damping material, distributed substantiallyuniformly throughout the coating, and submerged therein.

In testimony whereof ll afiix my signature. JQHN A. STEURER.

